This grant is requesting a Hitachi H-7000 transmission electron microscope for use by investigators in the Departments of Medicine and Surgery at the Clinical Center of the School of Medicine and Biomedical Sciences of the State University of New York at Buffalo. This scope is to replace a Siemens Elmskop 1A which has been used by investigators in this building for approximately the past 25 years. The instrument will be maintained and operated by an experienced individual, and an internal advisory committee has been established to facilitate the use and care of the instrument. A major group of nine users have been identified. All have active grant support from the National Institutes of Health. The projects includes studies into the pathogenesis of gonococcal infections during human infection with emphasis on studies of the antigenic nature of the oligosaccharides of the lipooligosaccharide component of the organism. Similar studies are described for studies of Haemophilus influenzae in secretions obtained from the middle ear during otitis media and from the cerebrospinal fluid after meningitis. One group has described studies to investigate intracellular calmodulin traffic using immunoelectron microscopic analysis. In addition, this group plans utilize the electron microscope to study the glucose transport protein in the brain of aged rats. Plans are also described for the microscope to be used to investigate meningeal tissue for receptor to the meningococcal C capsular polysaccharide using anti-idiotype antibodies. Three physiologic studies would use this instrument to access the ultrastructural changes in cardiac and pulmonary tissue after experimental stress. These experiments were initially described at the light microscopic level in their proposals. Accessibility to the electron microscope would greatly enhance the quality of the data obtained from these studies. Finally, epitope mapping analysis of the HIV gp120/gp41 by the development of monoclonal reagents has led to the identification of antibody reagents which would allow analysis of the intracellular movement of this protein during human T4 cell infection. In addition to specific aspects of these proposals, the microscope will play in an important role in the day to day evaluation of materials, eg, presence of pili on Neisseria, and the quality and purity of preparations used in other experiments vital to these projects eg, analysis of envelope preparations for contaminants or the analysis of pyocin preparations for integrity of the particles.